1. Field of the Invention
The present invention relates to a keyboard switch for a lidded computer case. More particularly, the present invention relates to a keyboard switch that retracts multiple key switches from a stand-by orientation to a narrower storage orientation.
2. Description of the Prior Art
Conventionally known is a keyboard switch that retracts a plurality of key switches to a storage orientation within a lidded computer case.
A shown in FIGS. 7 through 9, a conventionally known keyboard switch (not shown) contains a plurality of key switches 100 each containing a cross-link 101. Each cross-link 101 includes a first link member 101a and a second link member 101b pivotably coupled at intermediate pivot points 101c. Each cross-link 101 is located between a key top 102 and a support plate 107.
A bottom end of first link member 1O1a hinges to a hinged end portion 110 and couples pivotally to a support projection 109 formed from support plate 107. A top end of first link member 101a, having a pivotal and slidable end portion 111, engages a guide portion 105 formed on the underside of key top 102. Thus, first link member 101a both pivots and slides in a left-to-right direction in FIGS. 7 through 9.
A bottom end of second link member 101b, having a pivotable and slidable end portion 112, engages an engagement long hole 108. A top end of second link member 101b hinges to a hinged end portion 113 and couples pivotally to the underside of key top 102.
In FIG. 7, keyboard switch 100 is shown in a stand-by position. A dome shaped rubber elastic portion 114 is disposed under key top 102, and serves as a return spring. Elastic portion 114 is in contact with the underside of a depressing portion 106 projected perpendicularly from the bottom side of key top 102.
Elastic portion 114 is formed integrally with a rubber sheet 104 on switch sheet 103. A membrane switch portion 103a is formed integrally with switch sheet 103. Switch sheet 103 is disposed continuously under keyboard switch 102. Rubber sheet 104 and switch sheet 103 are slidable together on support plate 107.
Depressing key top 102 (from above in FIG. 7) causes key top 102, guided by cross-link 101, to lower in parallel with switch sheet 103, toward switch sheet 103, without significantly inclination. Depressing key top 102, depresses depressing portion 106 and deforms elastic portion 114. Deformed elastic portion 114 contacts and actuates membrane switch portion 103a.
In FIG. 8, keyboard switch 100 is shown in a fully depressed position. In a fully depressed position, deformed elastic portion 114 contacts switch portion 103a.
A computer unit case, mounting a keyboard switch, connects rotatably with a lid 115 which covers key tops 102 in a closing motion.
In FIG. 9, as lid 115 closes, rubber sheet 104 and switch sheet 103, slide relative to support plate 107 (leftward in FIG. 9), in response to the closing motion. Thus, deformed elastic portion 114 retracts into a storage recessed portion 116 formed under key top 102.
When deformed elastic portion 114 retracts, key top 102 and cross-link 101 drop due to their own weight provide a low profile. When deformed elastic portion 114 retracts, it does not contact switch portion 103a.
Retracting elastic portion 114 into storage recessed portion 116 allows elastic portion 114 to return to an original dome shape. Retracting elastic portion 114 into storage recess 116 also removes contact with depressing portion 106. As a result, conventional key switch 100 allows computer units to reduce overall thickness during the closing of lid 115. However, the distance between support plate 107 and key top 102 may not be made less than the free-state height of elastic portion 114 thus limiting the minimum thickness of the computer unit.
Furthermore, the need for depressing portion 106 and storage recess 116, cause each key top 102 and, hence keyboard switch 100, to be correspondingly larger. Additionally, retracting return spring 114 into storage recess portion 116 requires sliding, thereby requiring the lid 115 mechanism to be larger and more complex. Also, sliding integral rubber sheet 104 and elastic portion 114 require a relatively large force.
A conventional keyboard switch (not shown) allows rubber sheet 104 and integral elastic portion 114 to slide relative to switch sheet 103. However, this type of conventional keyboard switch has a possibility of malfunction. To limit this possibility, a friction-limiting membrane, for example polyester, has been placed between rubber sheet 104 and switch sheet 103, thus increasing cost.